package cn.edu.zzuli;

import java.util.concurrent.ExecutionException;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.ForkJoinTask;
import java.util.concurrent.RecursiveTask;

/**
 * @Date: 2021/3/10 21:12
 * @Author: 绯色下午茶
 * @Description: 分支合并框架
 */
class MyTask extends RecursiveTask<Integer> {
    public static final Integer ADJUST_VALUE = 10;
    private int begin;
    private int end;
    private int result;

    public MyTask(int begin, int end) {
        this.begin = begin;
        this.end = end;
    }

    /**
     * 10以内的数不用计算
     *
     * @return
     */
    @Override
    protected Integer compute() {
        if (end - begin <= ADJUST_VALUE) {
            for (int i = begin; i <= end; i++) {
                result = result + i;
            }
        }else {
            int middle = (end+begin)/2;
            MyTask task = new MyTask(begin,middle);

            MyTask task1 = new MyTask(middle+1,end);

            task.fork();
            task1.fork();

            result = task.join()+task1.join();
        }
        return result;
    }
}

public class ForkjoinDemo {
    public static void main(String []args) throws ExecutionException, InterruptedException {
        MyTask myTask = new MyTask(0,100);

        ForkJoinPool threadPool = new ForkJoinPool();
        ForkJoinTask<Integer> forkJoinTask = threadPool.submit(myTask);
        System.out.println(forkJoinTask.get());
        threadPool.shutdown();
    }
}
